Method for completing and working over wells



1 Dec. 31, 1957 1'. A. HUBER METHOD FOR COMPLETINGIAND WORKING OVER WELLS Filed 091;; 19, 1953 k m at //v VENT-0R. Theodore A. Huber; B)-

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res ateflf METHOD FOR COMPLETING AND WORKING OVER WELLS Theodore A. Huber, Houston, Tex., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application October 19, 1953, Serial No. 386,718

13 Claims. (Cl. 166-21) The present invention is directed to a method for completing and working over wells. More particularly, the invention is directed to a method for producing hydrocarbons from a plurality of subsurface earth formations. In its more specific aspects, the invention has to do with a method for recompleting wells to produce hydrocarbons from a plurality of formations.

The present invention may be briefly described as a method for completing and working over wells which have been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which have a casing cemented in the well. The steps of the invention comprise locating or arranging the tubing in the well or wells with the lower end of the tubing arranged immediately above an upper of the productive strata. The casing is then perforated in the upper productive stratum and hydrocarbons are produced from the upper stratum until the production of hydrocarbons, such as oil, becomes uneconomical, such as by salt water and/or gas encroachment. Thereafter the perforations in the casing in the upper productive stratum are sealed by cementing or the like and the casing perforated in a lower of the strata and production of hydrocarbons had from the lower productive stratum. During this series of operations, the tubing is maintained at its location with its lower end above the upper productive stratum without any movement whatsoever, such as by manipulation of the tubing.

The invention will be further illustrated by reference to the drawing in which Figs. 1 to 8 illustrate a stepwise practice of the present invention and is a preferred mode.

Referring now to the drawing and particularly to Fig. 1, a well 11 has been drilled in the earth penetrating a plurality of hydrocarbon productive strata illustrated by strata A to D. The well has arranged therein a casing 12 which has been cemented in place with cement 13. The casing 12 has arranged in it a tubing 14 extending downwardly in the well from the earths surface, not shown, with the lower end of the tubing arranged at a point immediately above hydrocarbon productive stratum A.

The hydrocarbon strata A to D are separated by nonproductive strata, such as strata 15, 16 and 17.

In the illustration with respect to Fig. l the well has been arranged with the tubing 14 in place and the drilling mud cleaned out of the hole, such as by washing with salt water or other clean fluid.

Referring now to Fig. 2, a tubing gun perforator 19 is lowered into the well 11 on a wire line 20 or other suspension means and the like through the tubing 14 to a point adjacent the formation or stratum A. The tubing gun perforator 19 is then operated by firing to cause the formation of a plurality of perforations 21 which penetrate the casing 12, the cement 13 and the formation A. Thewell is then brought in and production had through the perforations 21, the flow being upward in the well through the casing 12 and tubing 14 as indicated in Fig. 3,

the gun perforator 19 having been removed from the well by means of the wire line 20.

After production has been had from the stratum A and the production of oil or other hydrocarbons has become uneconomical-such as by water or gas encroachment, it is desirable, in accordance with the present invention, to obtain production from other of the productive strata B to D as may be desired. However, to obtain production from formations or strata B to D it becomes necessary, in accordance with the present invention, to seal off the perforations 21. This may suitably be accomplished by lowering through the tubing 14 by means of a wire line or other suspending means and the like a tubular member, such as 24. This tubular member may be landed in or attached to the interiorof the tubing 14 and suspended therein to form a path of flow from the open lower end of the tubing to a point a substantial distance below the end of the tubing. After the path of flow has been established, cement may be pumped down through the tubing 14 and the member 24followed by other fluid, such as oil, salt water and the like, to spot a body of cement 25 adjacent the perforations 21, the body of cement 25 being followed by a column of salt water or other clean fluid 26, both the fluid cement 25 and the salt water 26 being flowed down the well through the tubing 14and the extension member 24. The cement may be followed by mud or by any fluid or may be a continuous column of cement to the surface.

After the body of cement 25 has been arrangeduadjae cent the perforations 21, pressure is imposed on the body of cement 25 preferably through the tubing 14 or through the annulus A by pumping salt water or any other clean fluid down the tubing 14 and the member 24 or down I the casing annulus A and also by imposing pressure on the salt water 26 below the body of cement 25. This causes the cement in the body 25 to pass into the perfora tions 21 and form a filter cake, such as 27, in the perforations which will seal off the formation A from the casing 12. After the filter cake 27 has been formed in the perforations 21, the tubing extension member 24 is withdrawn from the tubing 14. Prior to and/or during the withdrawing of the tubing extension member, the ex: cess fluid cement 25 remaining in the well is circulated out by the pressure put on the annulus A which causes the cement to proceed up through the tubing extension 24 and the tubing 14, the tubing extension 24 being raised during the time of circulation as desired. Thus referring to Figs. 5 and 6 after the filter cake 27 hasbeen built up allowing a suflicient time to elapse, say 15 minutes to 5 hours, the pressure is taken off of the tubing 14 and the extension member 24 and the cement 25 and salt water 26 allowed to flow back up thetubing 14 before the extension member 24 has been or while the extension member 24 is being withdrawn.

Fig. 6 shows the filter cake 27 in the perforations 21 and the cement 25 being circulated out the tubing 14 and the tubing extension 24 being withdrawn.

With the filter cake 27 sealing the perforations 21, the gun perforator 19 is lowered again into the well by means or the wire line 20 to a lower of the strata, such as stratum C, and the gun perforator operated to form perforations 30 in the stratum C. After the tubing gun perforator has formed perforations 30 in the stratum C, the gun 19 is removed from the well through the tubing 14. Thereafter production is had from the stratum C.as illustrated in Fig. 8, the oil or other hydrocarbons flowing up the casing 12 and tubing 14 to the surface.

In the practice of the present invention, it is desirable to employ a fluid for the several operations which is free from mud and sand. This clean fluid may be water, salt water, oil, a gel of hydrocarbons, gel acid, and the like. This permits a satisfactory filter cake of cement to form in the perforation and to seal the formation or stratum, suchas A, from the casing 12.

The cement employed is preferably a low water loss cement slurry, such as a modified Portland cement, contalning bentonite and a dispersing agent such as described and claimed in the patent to R. A. 'Salathiel, U. S. 2,582,459. Other low water loss cements are oil-emulsion cements and other chemically prepared low Water loss cements available on the market. The cement employed in practicing the present invention must be of such a nature that it will allow the building up of sufficient filter cake 111 the perforations to seal the perforations and to seal off the formation from which production has been had and which is to be sealed. It is desirable that the body of cement in the casing be allowed to remain in the casing until the filter cake has formed and such may be accomplished by maintaining a sufiicient amount of pressure on the cement during a period of time ranging from about l to 5 hours; usually about 3 hours will be sufiiclent to form the filter cake. The pressure employed should be less than the incipient breakdown pressure of the particular formation which has been penetrated and which is tobe sealed. I

In practicing the present invention, it may be desirable to conduct the squeezing operation with the pressure put on the annulus A through the casing or to apply pressure through the tubing 14 and extension member 24 or by applying pressure through the tubing or the casing at the same time. i

The invention is susceptible to many modifications. For example, it may be desirable to produce from an upper of a series of strata, such as A to D and then go to a lower of the strata, such as C, as illustrated, and then to proceed further by sealing ed the. stratum C and perforating in the stratum B. Thereafter the stratum D might be subsequently penetrated. and production had from that particular strata.

While the present invention is susceptible to obtaining oil from a plurality of zones or oil producing intervals, it is to be emphasized that it is particularly applicable to production of oil and other hydrocarbons from a series of earth strata containing such hydrocarbons which may or may not be separated by non-productive strata or in-' tervals. Thus, it may be desirable to seal oil water and/or gas in a particular productive interval and the present invention is admirably suited for that purpose. Such producing intervals arev encountered more frequently in the Gulf coastal. area than in other areas but it is to be understood that my invention is susceptible to practice in any series ofv earth. strata which are separated by non-productive strata or intervals.

As pointed outbefore, the present invention is susceptible for. use in sealing off gas and/or water encroachment in a particular productive interval or stratum- Thus it may be desirable to seal off gas and/ or water and then produce in the same interval by perforating higher or lower down or, reperforating in the stratum or interval after sealing off the intrusion of undesirable fluids, such as gas and/or water. Also the present invention may be employed where the casing has been perforated prior to or after running in the tubing, such as shown in Figs. 1 and 2. In such instance where the stratum, such as A, may have been perforated initially and then tubing, such as 14, set, such as in Figs. 1 and 2, the present. invention may beemployed to seal off or close the formation A to the casing 12 and thereafter the present invention employed to obtain production from a lower stratum or from a lower or higher zone in the same stratum as has been described.

The present invention is quite advantageous in that the necessity for using heavy duty lifting equipment is eliminated; Furthermore, it is possible to operate in recompletion jobs in which an upper strata'has been produced and it is desired to produce from a lower stratum without the necessity of drilling out cement or manipulating the tubing string as has been the practice heretofore. Thus all operations may be conducted by means of light equipment on a wire line.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patcut is:

1. A method for completing and working over a well which has been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which has a casing cemented in the well which comprises the steps of locating a tubing in said well with its lower end arranged immediately above the uppermost productive stratum, perforating said casing at a level adjacent said uppermost productive stratum, producing hydrocarbons from said uppermost productive stratum, sealing said perforations in said uppermost productive stratum by forming and applying pressure to a body of settable sealing material adjacent said uppermost productive stratum and above the bottom of the well, perforating said casing at a level adjacent a lower productive stratum below the sealed perforations and producing hydrocarbons from said lower productive stratum, said tubing being maintained at said location against any movement in said steps.

2. A method for completing and working over a well which has been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which has a casing cemented in the well, which comprises the steps of locating a tubing in said well with its lower end arranged immediately above the uppermost productive stratum, lowering a perforator through said tubing into said casing to a level adjacent said uppermost productive stratum, perforating said casing and said uppermost productive stratum with said perforator, producing hydrocarbons through said perforations from said uppermost productive stratum, spotting fluid cement in said casing adjacent said perforations in said uppermost stratum and above the bottom of the well, squeezing cement into said perforations to seal off the uppermost productive stratum, removing excess fluid cement from said casing through said tubing, lowering a perforator through said tubing intosaid casing to a level adjacent a lower productive stratum below the sealed perforations and causing said perforator to form perforations in said casing and producing hydrocarbons through said perforations from-said lower productive stratum, said tubing being maintained in said locationagainst movementin said steps.

3. A method for completing and working over a well which has been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which has a casingcemented in the well, which comprises thesteps of locating a tubing in said well with its lower endarranged immediately above the uppermost productive stratum, lowering a-gun perforator through said tubing into said casing to a level adjacent said uppermost productive stratum, perforating said casing and said uppermost productive stratum with said gun perforator, producing oil through said perforations from said uppermost productive stratum until production of oil has become uneconomical, spotting fluid cement in said casing at a level adjacent said perforations in said uppermost stratum and above the bottom of the well, squeezing cement into said perforations to seal off the uppermost stratum by applying pressure on said cement, removing excess fluid cement from said. casingthrough said tubing,

lowering a gun perforator. through said tubing to a level.

adjacent. a lower productive stratum below the sealed perforations and causing said perforator to form perforations in said casing. and said lower productive stratum, said tubing being maintained in said. location against movement in said steps.

4. A method for completing and working-over" a well has been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which has a casing cemented in the well which comprises the steps of locating a tubing in said well with its lower end arranged immediately above the uppermost productive stratum, lowering a gun perforator through said tubing into said casing to a level adjacent said uppermost productive stratum, perforating said casing and said uppermost productive stratum with said gun perforator, producing oil through said perforations from said uppermost productive stratum until production of oil becomes uneconomical, placing fluid cement in said casing through said tubing, spotting said cement in said casing at a level adjacent said perforations in said uppermost productive stratum and above the bottom of the well, squeezing said cement into said perforations to seal off the uppermost productive stratum by applying pressure on said cement within said casing, removing excess fluid cement from said casing through said tubing, lowering a gun perforator through said tubing to a level adjacent a lower productive stratum below the sealed perforations and causing said gun perforator to form perforations in said casing and said lower productive stratum and producing oil through said perforations from said lower productive stratum, said tubing being maintained in said location against movement in said steps.

5. A method for completing and working over a well which has been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which has a casing cemented in the well, which comprises the steps of locating a tubing in said well with its lower end arranged immediately above the uppermost productive stratum, lowering a gun perforator through said tubing into said casing to a level adjacent said uppermost productive stratum, perforating said casing and said uppermost productive stratum, producing hydrocarbons through said perforations from said uppermost productive stratum, spotting fluid cement in said casing adjacent said perforations in said uppermost productive stratum and above the bottom of the well, squeezing fluid cement into said perforations to seal off said uppermost productive stratum by applying pressure on said cement in said casing, removing excess fluid cement from said casing through said tubing by circulating a fluid down the casing to carry said excess fluid cement up through the tubing, lowering a perforator through said tubing to a level adjacent a lower productive stratum below the sealed perforations and causing said perforator to form perforations in said casing and in said lower productive stratum and producing hydrocarbons from said lower productive stratum, said tubing being maintained in said location against movement in said steps.

6. A method for completing and working over a well which has been drilled into an oil productive stratum containing undesirable fluids and in which a casing has been cemented in place and then perforated in said stratum, which comprises producing oil from said well from said oil productive stratum through a tubing located in said well with its lower end arranged at a point immediately above said stratum until the production of undesirable fluids with said oil increases to an uneconomical extent, spotting an excess amount of fluid cement in said casing adjacent the perforations, and above the bottom of the well, squeezing said fluid cement into said perforations, removing excess fluid cement from said casing, perforating said casing in said oil productive stratum at a point below the sealed perforations, and then again producing oil from said stratum without manipulating said tubing.

7. A method in accordance with claim 6 in which the undesirable fluids comprise gas.

8. A method in accordance with claim 6 in which the undesirable fluids comprise water.

9. A method for completing and working over a well which has been drilled into an oil productive stratum containing undesirable fluids and in which a casing has been cemented in place, which comprises the steps of locatingla tubing in said well with its lower end arranged immediately above said stratum, lowering a perforator through said tubing into said casing and perforating said casing adjacent said stratum, producing oil through said perforated casing through said tubing until the production of undesirable fluids with said oil increases to an uneconomical extent, spotting an excess amount of fluid cement in said casing adjacent the perforations therein and above the bottom of the well, squeezing said cement into said perforations, removing excess fluid cement from said casing, lowering a gun perforator through said tubing and perforating said casing in said oil productive stratum at a point below the sealed perforations and then again producing oil from said stratum without manipulating said tubing.

10. A method in accordance with claim 9 in which the undesirable fluids comprise gas.

11. A method in accordance with claim 9 in which the undesirable fluids comprise water.

12. A method for completing and working over a well which has been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which has a casing cemented in the well which comprises the steps of locating a tubing in said casing with its lower end arranged immediately above the uppermost productive stratum, perforating said casing at a level adjacent a selected productive stratum above the lowermost productive stratum, producing hydrocarbons from said selected productive stratum, sealing said perforations and said selected productive stratum by forming and applying pressure to a body of settable sealing material adjacent said selected productive stratum and above the bottom of the well, perforating said casing at a level adjacent a productive stratum below said selected productive stratum and producing hydrocarbons from the productive stratum below the selected productive stratum, said tubing being maintained at said location against any movement in said steps.

13. A method for completing and working over a Well which has been drilled through a plurality of hydrocarbon productive strata separated by non-productive strata and which has a casing cemented in the well which comprises the steps of locating a tubing in said casing with its lower end arranged immediately above the uppermost productive stratum, lowering a gun perforator through said tubing into said casing to a level adjacent a selected first productive stratum above the lowermost productive stratum, perforating said casing and said selected first productive stratum with said gun perforator, producing oil through said perforations from said selected first productive stratum until production of oil becomes uneconomical, spotting fluid cement in said casing at a level adjacent said perforations in said selected productive stratum and above the bottom of the well, squeezing said cement into said perforations to seal off the selected productive stratum by applying pressure on said cement within said casing, removing excess fluid cement from said casing through said tubing, lowering a gun perforator through said tubing to a level adjacent a second productive stratum below said selected first productive stratum and causing said gun perforator to form perforations in said casing and said second productive stratum and producing oil through said perforations from said second productive stratum, said tubing being maintained in said location against movement in said steps.

References Cited in the file of this patent UNITED STATES PATENTS 2,016,919 Church Oct. 8, 1935 (Other references on following page) 7 UNITED STATES PA IENTS "wens Mar. TO, 1936 Pew July 20, 1 937 Chonette et a1. Dec. 7, 1937 5 Armentrout et a1. Sept. 12, 1939 8 Brown Ian. 9, 1940 Salnikov Nov. 4, 1941 Reed 1.. Feb, 1-5., 1944 Baker Mar. 14, 1944 Thompson et a1. Mar. 6, 1951 Huber June 12, 1956 

1. A METHOD FOR COMPLETING AND WORKING OVER A WELL WHICH HAS BEEN DRILLED THROUGH A PLURALITY OF HYDROCARBON PRODUCTIVE STRATA SEPARATED BY NON-PRODUCTIVE STRATA AND WHICH HAS A CASING CEMENTED IN THE WELL WHICH COMPRISES THE STEPS OF LOCATING A TUBING IN SAID WELL WITH ITS LOWER END ARRANGED IMMEDIATELY ABOVE THE UPPERMOST PRODUCTIVE STRATUM, PERFORATING SAID CASING AT A LEVEL ADJACENT SAID UPPERMOST PRODUCTIVE STRATUM, PRODUCING HYDROCARBONS FROM SAID UPPERMOST PRODUCTIVE STRATUM, SEALING SAID PERFORATIONS IN SAID UPPERMOST PRODUCTIVE STRATUM 